On Fri, 25 Jul 2025 at 11:08, Jie Gan <jie.gan@xxxxxxxxxxxxxxxx> wrote:
>
> Retrieving the helper device of the specific coresight device based on
> its helper_subtype because a single coresight device may has multiple types
> of the helper devices.
>
> Signed-off-by: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
> ---
> drivers/hwtracing/coresight/coresight-core.c | 35 ++++++++++++++++++++
> drivers/hwtracing/coresight/coresight-priv.h | 2 ++
> 2 files changed, 37 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 042c4fa39e55..018b1119c48a 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -580,6 +580,41 @@ struct coresight_device *coresight_get_sink(struct coresight_path *path)
> }
> EXPORT_SYMBOL_GPL(coresight_get_sink);
>
> +/**
> + * coresight_get_helper: find the helper device of the assigned csdev.
> + *
> + * @csdev: The csdev the helper device is conntected to.
> + * @type: helper_subtype of the expected helper device.
> + *
> + * Retrieve the helper device for the specific csdev based on its
> + * helper_subtype.
> + *
> + * Return: the helper's csdev upon success or NULL for fail.
> + */
> +struct coresight_device *coresight_get_helper(struct coresight_device *csdev,
> + int type)
> +{
> + int i;
> + struct coresight_device *helper;
> +
> + /* protect the connections */
> + mutex_lock(&coresight_mutex);
> + for (i = 0; i < csdev->pdata->nr_outconns; ++i) {
> + helper = csdev->pdata->out_conns[i]->dest_dev;
> + if (!helper || !coresight_is_helper(helper))
> + continue;
> +
> + if (helper->subtype.helper_subtype == type) {
> + mutex_unlock(&coresight_mutex);
> + return helper;
> + }
> + }
> + mutex_unlock(&coresight_mutex);
> +
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(coresight_get_helper);
> +
> /**
> * coresight_get_in_port_dest: get the in-port number of the dest device
> * that is connected to the src device.
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index e51b22b8ebde..f80122827934 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -158,6 +158,8 @@ void coresight_path_assign_trace_id(struct coresight_path *path,
> enum cs_mode mode);
> int coresight_get_in_port_dest(struct coresight_device *src,
> struct coresight_device *dest);
> +struct coresight_device *coresight_get_helper(struct coresight_device *csdev,
> + int type);
>
> #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM3X)
> int etm_readl_cp14(u32 off, unsigned int *val);
> --
> 2.34.1
>
Reviewed-by: Mike Leach <mike.leach@xxxxxxxxxx>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
